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Alan, (are you the Alan I met once who also once worked for the National insurance in Dunedin?)
no we TELSTRA ( as in telecom Australia) supplied the cable the radial distance is about 22km, but actual distance is about 35 KM. is was sort of dark fibre but telstra insisted in the 9036 box ( in a telephone exchange on the way) to ensure that we did not use that fibre for anything more than the 10 MBit/sec Escon we promised.
Phil Steele ( if you are, then we have met... thanks John Mycroft)
-----Original Message-----
From: owner-vse-l@Lehigh.EDU [mailto:owner-vse-l@Lehigh.EDU]On Behalf Of
Allan Peterson
Sent: Friday, 21 January 2005 11:18 AM
To: VSE Discussion List
Subject: RE: ESCON distance
Did you have to run your own "dark fibre" or was your local Teloc able to supply it without too many joins etc?
Allan
-----Original Message-----
From: owner-vse-l@Lehigh.EDU [mailto:owner-vse-l@Lehigh.EDU]On Behalf Of
Phil Steele
Sent: Friday, 21 January 2005 11:46 a.m.
To: VSE Discussion List
Subject: RE: ESCON distance
Hi Augie,
( I presume you do indeed mean ESCON (not Ficon, because the rules all change then)
we run two sites 35 Km apart each with a Z/800 and escon attached HDS 9980V ( I am sure SHARKS would be the same) . Before the HDS boxes we had RAMAC-2 dasds and subsystems, and before them we had 3390s and 3990s ( and 9672s and escon-equipped 3090-17ts).In all cases, each site's cpus accessed the other site's dasd via escon. we did need 9033 escon directors at each site with a 9036 in the middle ( fibre provider's requirement that was) the escon talked to each other via laser escon ( that is what gave us the distance) over that dark fibre. Now, we use a DWDM , and it handles the distance side of things and that escon directors now talk directly to each other over the DWDM via LED ports ( were it not for the fact that they are really handy boxes anyway, we would not need them any more, since the DWDM handles the distance isse now).
We have always been happy with this arrangement, but I must warn about a nasty little thing called escon 'DROOP' (lovely name).
Because Escon is what is called a 'CHATTY' protocol its USEFUL data rate slows down a lot, the further you go with it. In our case (with our typical disk blocksizes of 4KB) the intersite disk traffic runs at about 1 MB/sec, ( we got 4.5 from the LOCAL RAMACS, and of course much more from the 9980Vs ( or sharks, I am sure). I think it would start getting even worse if the sites were much further apart... ( Einstein has a lot to answer for!!!)
I repeat this droop is an ESCON design attribute, not FICON or native fibre.
I hope some of this helps ... Phil Steele
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